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Question 224-1 : Minimum ground based augmentation system gbas plan coverage is ? [ Certification weather ]
15 nm from the landing threshold point within 35° apart the final approach path and 10° apart between 15 and 20 nm.
.a ground based augmentation system gbas is an augmentation system in which the user receives augmentation informationdirectly from a ground based transmitter...annex 10 aeronautical telecommunications.category i precision approach and approach with vertical guidance..the gbas coverage to support each category i precision approach or approach with vertical guidance shall be as follows, except where topographical features dictate and operational requirements permit..a laterally, beginning at 140 m 450 ft each side of the landing threshold point/fictitious threshold point ltp/ftp and projecting out ±35 degrees either side of the final approach path to 28 km 15 nm and ±10 degrees either side of the final approach path to 37 km 20 nm.... 2610
Question 224-2 : The vdb vhf data broadcast broadcasts the gbas signal within its coverage area to avionics in gbas equipped aircraft. the vdb signal provided is ?
Error correction data, integrity data and approach data for one or more runways.
.one ground station can support all the aircraft subsystems within its coverage, providing the aircraft with approach data, corrections and integrity information for gnss satellites in view via a vhf data broadcast vdb.
Question 224-3 : Which statement is correct about the sbas satellite based augmentation systems ?
In an sbas the pseudo range corrections are sent to the users by geostationary satellites.
.a gps based sbas uses satellites to transmit corrections to users. the pseudo range measurements to these geostationary satellites can be made as they also transmit a valid gps navigation message on the gps frequency..sbas station network measures the pseudo range between the ranging source and an sbas receiver at the known locations and provides separate corrections for ranging source ephemeris errors, clock errors and ionospheric errors. the user applies corrections for tropospheric delay.
Question 224-4 : Which statement is correct about glonass/navstar gps/galileo ?
All three systems use time measurement to determine a position.
.they are refering to time measurement, they are not using same frequencies moreover 2 bands for glonass and navstar, 3 bands for galilieo..glonass.each satellite transmits navigation signals on two frequencies of l band, l1 1.6 ghz and l2 1.2 ghz...gps.each satellite broadcasts ranging signals on two uhf frequencies. l1 1575.42 mhz and l2 1227.6 mhz...gallileo.signals will be transmitted in three frequency bands 1164 1215 mhz, 1260 1300 mhz and 1559 1591 mhz 1559 1591 mhz will be shared with gps on a non interference basis.
Question 224-5 : Gps time can be converted to utc by application of the ?
Utc parameters sent in the navigation message.
. utc parameters are factors determining the difference between gps time and utc.
Question 224-6 : Utc parameters is the difference between ?
Gps time and utc.
. utc parameters are factors determining the difference between gps time and utc.
Question 224-7 : Errors in gps satellites orbits are due to ?
The solar wind and gravitation of sun, moon and planets.
.gps satellites are required to follow orbital paths in order to provide accurate timing signals. they are subject to interference in the same way as any other satellite from a number of sources, these including solar winds plus gravitational effect of other bodies such as the sun, moon and planets.
Question 224-8 : When a gps receiver is using barometric altitude as an augmentation to raim receiver autonomous integrity monitoring ?
The number of satellites to perform raim function may be reduced by one.
.raim receiver autonomous integrity monitoring is technique whereby a receiver processor determines the integrity of the navigation signals...raim is achieved by consistency check among pseudo range measurements, it requires 5 satellites and a 6th is for isolating a faulty satellite from the navigation solution...if gps receiver uses barometric altitude as an augmentation to raim, the number of satellites needed for the receiver to perform the raim function may be reduced by one.
Question 224-9 : Assume that one of the gps/navstar satellites used by the receiver is faulty and that the position dilution of precision pdop has relatively low value when signals of the gps satellites is received including faulty , the raim software in the receiver is ?
Able to detect that one satellite that is faulty and identify which one.
.raim receiver autonomous integrity monitoring is a technique whereby a receiver processor determines the integrity of the navigation signals. raim is achieved by consistency check among pseudo range measurements..the basic raim requires 5 satellites but a 6th is necessary for isolating a faulty satellite from the navigation solution...the position dilution of precision pdop is the geometric effect resulting from satellites being too close together. satellites that appear farther apart in the sky provide a more accurate position solution than ones close together. in the latter case, the position accuracy is degraded in a similar fashion to when position lines from ground based navaids navigational aids are less than 45°. since the ephemeris of each satellite is known by the gps global positioning system receiver, it is possible to calculate which combination of gps satellites provides the best geometry at a given time. this is translated into a figure called the position dilution of precision pdop. since the satellites move across the sky relative to the user, the pdop is always changing. a low pdop is better. a pdop of 4 to 6 is considered good. position solutions calculated when the pdop is from 6 to 10 should be used cautiously because they may have significant error. a pdop that is above 10 indicates unacceptable error.. 2611.the icao international civil aviation organization states that a pdop of less than 6 is required for en route navigation, with a pdop of 3 or less required for nonprecision approaches i.e., not ils types.
Question 224-10 : How long does it take a glonass satellite to orbit the earth ?
11 hours 15 minutes.
. glonass constellation. 24 satellites in three orbital planes with 8 equally displaced by 45° of latitude. a near circular orbit at 19 100 km at an inclination of 64.8° to the equator 20200 km and 55° for gps/navstar satellites. each orbit is completed in 11 hours 15 minutes approximately 12 hours for navstar/gps.
Question 224-11 : Using gps, the primary position information is in the form of ?
Spheres, with the satellites in the centre of the spheres.
Question 224-12 : Which statement about satellite based augmentation system sbas is correct ?
The use of sbas improves both the accuracy and the integrity of the position of the user.
. the principle of a sbas to measure on the ground the signal errors transmitted by gnss satellites and transmit differential corrections and integrity messages for navigation satellites.
Question 224-13 : Which of the following is not improved by the application of differential gps ?
Multi path effects.
Question 224-14 : In egnos and waas systems the correction for an aeroplane's gnss receiver are broadcast ?
Via geostationary satellite.
.the geostationary satellite receives the data and transmits it on a broadcast to all users receivers. the broadcast is on the gps l1 frequency, modulated with a c/a code that is of the same category as the gps c/a codes uses the same time basis. this can be used to augment the signals from the navigation satellites.
Question 224-15 : Which of the following statements about the accuracy that can be obtained with the laas local area augmentation system of the satellite navigation system navstar gps is correct ?
The closer the receiver is to a laas ground reference station, the more accurate is the aircraft position fix.
.laas local area augmentation system is sometimes called gbas ground based augmentation systems.
Question 224-16 : Which of the following is the geodesic model used by the glonass system ?
Pz 90.
.glonass constellation. 24 satellites in three orbital planes with 8 equally displaced by 45° of latitude. a near circular orbit at 19 100 km at an inclination of 64.8° to the equator 20200 km and 55° for gps/navstar satellites. each orbit is completed in 11 hours 15 minutes approximately 12 hours for navstar/gps.. the datum used is pz 90 earth centred earth fixed.
Question 224-17 : At what approximate height above the wgs 84 ellipsoid are glonass satellites circling the earth ?
19100 km.
.glonass constellation. 24 satellites in three orbital planes with 8 equally displaced by 45° of latitude. a near circular orbit at 19 100 km at an inclination of 64.8° to the equator 20200 km and 55° for gps/navstar satellites. each orbit is completed in 11 hours 15 minutes approximately 12 hours for navstar/gps.. the datum used is pz 90 earth centred earth fixed.
Question 224-18 : What is the difference between satellites used by egnos and those used by gps ?
Egnos satellites are geostationary and gps satellites are not.
Ecqb03, august 2016....egnos consists of 3 geostationary inmarsat satellites which broadcast gps look alike signals uhf...egnos is designed to improve accuracy to 1 2m horizontally and 3 5 m vertically..integrity and safety are improved by alerting users within 6 seconds if a gps malfunction occurs up to 3 hrs gps alone.
Question 224-19 : What are the data elements transmitted by navstar gps satellites.1 offset of the satellite clock from utc.2 ephemeris data.3 health data.4 ionospheric delays.5 solar activity..the combination the regroups all of the correct statements is ?
1, 2, 3, 4.
.the navigation message contains. almanac data. ephemeris. satellite clock correction parameters. utc parameters. ionospheric model. satellite health data
Question 224-20 : One of the advantages of a satellite based augmentation system sbas over a ground based augmentation system gbas is ?
The coverage area of an sbas is much larger than that of a gbas.
. the principle of a sbas to measure on the ground the signal errors transmitted by gnss satellites and transmit differential corrections and integrity messages for navigation satellites... the principle of a gbas to mesure on ground the signal errors transmitted by gnss satellites and relay the mesured errors to the user for correction...the gbas ground segment consists of three or four gbas reference receivers that are sited typically on or near an airport property. these reference receivers track the signals from navigation satellites and pass pseudorange measurements and other information relevant to signal health and system performance monitoring to a central processing facility..the central processing facility uses the multiple, redundant observations of the pseudoranges to compute estimates of the pseudorange corrections for each satellite signal observed by the reference receivers..the central processing facility also monitors the signal integrity and computes parameters for each satellite that the user may use to determine the availability of the signal in space for a desired level of service and a given satellite geometry.. 2609.the differential corrections and integrity information are broadcast to the user...sbas systems improve the performance position accuracy of gps receivers by providing an additional signals coming from the geostationary satellites. the coverage area of an sbas is much larger than that of a gbas.
Question 224-21 : Raim is achieved ?
Within the receiver.
.raim receiver autonomous integrity monitoring is technique whereby a receiver processor determines the integrity of the navigation signals. raim is achieved by consistency check among pseudo range measurements, it requires 5 satellites and a 6th is for isolating a faulty satellite from the navigation solution..if gps receiver uses barometric altitude as an augmentation to raim, the number of satellites needed for the receiver to perform the raim function may be reduced by one.
Question 224-22 : Aaim aircraft autonomous integrity monitoring function is achieved with ?
A gps receiver and on board sensors.
.aaim uses the redundancy of position estimates from multiple sensors, including gnss, to provide integrity performance that is at least equivalent to raim..an example is the use of an inertial navigation system or other navigation sensors as an integrity check on gps data when raim is unavailable but gps positioning information continues to be valid.
Question 224-23 : The purpose of the aaim aircraft autonomous integrity monitoring function is to ?
Monitor satellite signals only.
.aaim uses the redundancy of position estimates from multiple sensors, including gnss, to provide integrity performance that is at least equivalent to raim..an example is the use of an inertial navigation system or other navigation sensors as an integrity check on gps data when raim is unavailable but gps positioning information continues to be valid.
Question 224-24 : By using egnos in combination with gps ?
The integrity is improved by reducing the mean failure reporting time from up to 3 hours to 6 seconds.
Question 224-25 : Which of the following statements concerning differential gps is true ?
Dgps can improve the accuracy of position information.
Ecqb03, august 2016.
Question 224-26 : The transmission band used by inmarsat is ?
Uhf.
.egnos consists of 3 geostationary inmarsat satellites which broadcast gps look alike signals uhf...egnos is designed to improve accuracy to 1 2m horizontally and 3 5 m vertically..integrity and safety are improved by alerting users within 6 seconds if a gps malfunction occurs up to 3 hrs gps alone.
Question 224-27 : How long does it take a galileo satellite to orbit the earth ?
14 hours.
.the core of the galileo constellation will consist of 30 satellites with 9 plus a spare replacement in each of the 3 planes in near circular orbit at an altitude of 23 222 km inclined at 56° to the plane of the equator..each orbit will take 14 hours..the signals will be transmitted in 3 frequency bands 1164 1215 mhz, 1260 1300 mhz and 1559 1591 mhz 1559 1591 mhz will be shared with navstar/gps l1 1575.42 mhz on a non interference basis.
Question 224-28 : The nominal galileo constellation consists of ?
30 satellites, 3 planes at an altitude of 23200 km.
.the core of the galileo constellation will consist of 30 satellites with 9 plus a spare replacement in each of the 3 planes in near circular orbit at an altitude of 23 222 km inclined at 56° to the plane of the equator..each orbit will take 14 hours..the signals will be transmitted in 3 frequency bands 1164 1215 mhz, 1260 1300 mhz and 1559 1591 mhz 1559 1591 mhz will be shared with navstar/gps l1 1575.42 mhz on a non interference basis.
Question 224-29 : In the nav message, the ephemeris refers to the exact ?
Position and orbit of the observed satellite.
Question 224-30 : If a gps malfunction occurs, integrity and safety are improved with egnos by alerting users within ?
6 seconds.
. egnos european geostationary navigation overlay service consists of 3 geostationary inmarsat satellites which broadcast gps look alike signals...egnos is designed to improve accuracy to 1 2m horizontally and 3 5 m vertically..integrity and safety are improved by alerting users within 6 seconds if a gps malfunction occurs up to 3 hrs gps alone.
Question 224-31 : Usually, a gps provides the following informations ?
X, y, z + ground speed + precise time reference.
.the gps supplies three dimensional position fixes and speed data, plus a precise time reference.
Question 224-32 : Sbas..how does the pseudo range correction of a gps system work ?
The pseudo range correction of a certain satellite is divided into separate correction of the ephemeris errors, clock errors and ionospheric errors.
Question 224-33 : The gnss constellation is composed of... satellites distributed in... orbits at... altitude. ?
24, 6, 20200 km.
.the satellites are in a nearly circular orbit of the earth at an altitude of 20 200 km 10 900 nm..the gps satellites are orbiting the earth in orbits inclined 55° to the plane of the equator..it consists of a notional constellation of 24 operational satellites the satellites are distributed in 6 orbital planes with at least 4 satellites in each..the orbital period is exactly one half a sidereal day 11 hours and 58 minutes so that the satellites pass over the same locations or almost the same locations every day.
Question 224-34 : What are the characteristics of a satellite based augmentation system sbas ?
The system is limited to areas of a certain proximity to the equator due to the nature of the transmission of the correction signal via geostationary satellite.
Ecqb04, november 2017.
Question 224-35 : Satellite based augmentation systems sbas certified and currently in use are ?
Egnos, waas, msas, gagan.
Ecqb04, november 2017....current satellite based augmentation systems are. egnos in western europe and the mediterranean. waas in usa. msas in japan. gagan in india..sbas systems improve the performance position accuracy of gnss/gps receivers by providing an additional signals coming from the geostationary satellites.
Question 224-36 : The time transmitted by a navstar gps satellite is ?
Gps.
Ecqb04, november 2017.
Question 224-37 : The acronym given to an aircraft based augmentation system abas whereby a receiver processor determines the integrity of the navstar gps navigation signals is ?
Raim receiver autonomous integrity monitoring.
Ecqb04, november 2017....raim receiver autonomous integrity monitoring is technique whereby a receiver processor determines the integrity of the navigation signals. raim is achieved by consistency check among pseudo range measurements, it requires 5 satellites and a 6th is for isolating a faulty satellite from the navigation solution..if gps receiver uses barometric altitude as an augmentation to raim, the number of satellites needed for the receiver to perform the raim function may be reduced by one.
Question 224-38 : In general a gnss receiver is able to determine ?
A three dimensional position, groundspeed and a precise time reference.
Gnss global navigation satellite systems are navigational systems that employ the use of many satellites orbiting the earth 24 is a technical minimum. each satellite transmits a constant coded electromagnetic message, called the prn pseudo random noise as well as a navigation message which contains extra data useful to our receiver.the prn code contains immensely precise timing data from when it was transmitted by the satellite. this timing data allows us to measure the time between when a message was sent and when it arrives at the receiver. as we know that these electromagnetic messages travel at the speed of light, we can calculate how far they have travelled between the transmitter and the receiver. this distance means that we can draw a 3d sphere around the satellite, called a range sphere, in the knowledge that the receiver is somewhere on that sphere edge.with multiple satellites in the sky above our receiver, this process can happen multiple times, every time giving us anther range sphere that narrows down a receiver's location further. for a 3 dimensional position fix to be made, we need 4 range spheres, and therefore 4 usable satellites in view. this is the basic principle of operation of all gnss systems. . this timing data does also mean that our receiver always has the exact time reference. not only this, but more modern gnss receivers can also pick up very slight changes in signal frequency that occur due to the doppler effect. the doppler effect is where waves electromagnetic in this case have a slightly higher detected frequency when the transmitter and receiver are coming together, but a lower frequency when moving apart. as we know the exact frequency that the signal should be l1 is 1575.42 mhz , and any expected movement of the satellites, our receiver can calculate its own ground speed using the combined doppler effect of all the satellites in view.
Question 224-39 : By using egnos in combination with gps ?
The integrity is improved by reducing the mean failure reporting time from up to 3 hours to 6 seconds.
Learning objective 062.06.02.02.09 explain that integrity and safety are improved by alerting sbas users within 6 seconds if a gps malfunction occurs....satellite based augmentation systems sbas..sbas uses the idea of differential gps dgps and does a very similar job to gbas, just over a much wider area...their geosynchronous orbits mean that they stay over the same place on the earth all the time, and can reduce gnss errors and increase integrity over a very large area...this means that there are multiple around the world, waas for the usa, egnos for europe, gagan for india, msas for japan, etc...accuracy is enhanced through the transmission of wide area corrections for gnss range errors, such as ephemeris, satellite clock errors and ionospheric propagation...integrity is enhanced by the sbas network quickly detecting satellite signal errors and sending alerts to receivers that they should not track the failed satellite...this means that sbas can reduce the notice time of a failure from a potential 3 hours standard gps to only 6 seconds sbas...signal availability can also be improved as the sbas transmits ranging signals from its satellites, on top of its other roles, it acts as an extra gnss satellite...sbas systems include reference stations, which are geographically distributed throughout the sbas service area, receive gnss signals and forward them to the master station...since the locations of the reference stations are accurately known, the master station can accurately calculate gnss range corrections over a very wide area.....sbas can be used to make aircraft gnss systems far more accurate on approaches 1 2 m horizontally and 3 5 m vertically , to allow for lower minimums on instrument approaches using this system...they are able to give vertical guidance on approaches also, similar to the role of baro vnav on lnav/vnav approaches...they can even be used to refine the gnss signal for lpv approaches localiser performance with vertical guidance which have decision heights as low as 200ft.
Question 224-40 : Assume that one of the satellites used by a gps receiver is faulty. when the signals of 5 satellites are received including the faulty one the raim software in the receiver ?
Is able to detect that one of the satellites is faulty but is unable to identify the faulty one.
Receiver autonomous integrity monitoring raim..raim is a technique which uses extra gnss satellites to improve the integrity of gnss location data. instead of the 4 satellite ranges required for a 3d gnss fix, using 5 satellites can mean that the onboard raim system can continuously measure different sets of 4 signals, making sure that every fix is consistent with the others. each fix excludes 1 satellite, so the receiver knows if they are all correct or not, thereby noticing if any one satellite becomes faulty, as all the seperate fixes will then be different from each other. this can tell us within a few seconds if a satellite that we are using becomes faulty, rather than waiting a potential 3 hours for it to be noticed and taken offline. this raim feature is called fault detection fd. it does not tell us which is the faulty satellite, as this is mathematically impossible to work out with so little data....if we use a second extra satellite, a total of 6 for a 3d fix , then we can also reliably calculate which is the faulty satellite and remove it from usage, called fault detection and exclusion fde.....the amount of required satellites can be reduced by 1 for 2d fixes, but these are not used unless barometric altitude is fed to the gnss system, which can allow an extra 'range sphere', and effectively acts like another satellite. this is an air based augmentation system and occurs in a different place in the learning objectives.
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